Valmet Valmet MCA, Инструкция по установке и эксплуатации, Страница: 29 / 66

7. Calibration
The Valmet MCA is delivered with factory calibration,
which means that it will measure consistency as soon
as you switch the power on. Factory calibration is per-
formed on the device in connection with final testing
using clean water.
We recommend that you calibrate the device again
when setting it up. This allows the device settings to
be optimized for the conditions in which it will be used.
Perform calibration by taking a consistency sample and
entering its laboratory value into Valmet MCA. When
you have performed this according to the instructions
in the next chapters, the status line on the display will
change from Factory Calibration to OK.
Calibration menu contains the following functions:
1 = S a m p l e t a k i n g
2 = E n t e r l a b
3 = O f f s e t c o r r e c t i o n
4 = F i l l e r
5 = C a l i b . h i s t o r y
6 = S a m p l e h i s t o r y
7.1. Sample Taking
In the main display, press the ESC button to move to
the Operations menu. Select Calibration/Sample taking.
Whenever a factory-calibrated device takes a
sample, it adjusts the measurement signal to the optim-
al level before taking the sample. This may cause a
small steplike change in the device's consistency
measurement. For this reason, the device may not be
kept on consistency control in this phase.
In addition, whenever a device that has been calib-
rated takes a sample, it checks whether the measure-
ment signal level is within an acceptable area. If the
signal level is outside the acceptable area, the device
suggests that the signal level be adjusted. The signal
level adjustment may cause a small step-like change
in the consistency measurement. Therefore you must
put consistency control on manual control if you allow
the device to adjust the signal level. A change in
chemical concentration may cause a need to adjust
the signal level.
The sample-taking display is as follows:
P r e s s s a m p l e - k e y
s t a r t s a m p l i n g .
C s = 3 . 2 6 %
S t a t u s : W A I T I N G
t o
Press the Sample button on the right side of the
display. The device begins averaging the measurement
result and a message "Sampling" appears on the Status
line. Go take a calibration sample, and then press the
Sample button again. The device finishes averaging
the measurement result and displays the result.
S a m p l i n g r e a d y .
A v e r a g e C s = 3 . 2 6 %
M i n = 3 . 2 0 M a x = 3 . 3 3
T = 5 6 . 3 C
In addition to showing the consistency average, the
device also shows the sampling period's minimum and
maximum values as well as the process temperature.
The minimum and maximum values indicate consist-
ency fluctuation during the sampling period. This fluc-
tuation should be small so that the consistency sample
is reliable. The sample you take goes to the Enter Lab
menu to await the laboratory value.
Press the ESC button to move back in the menus.
NOTE: If you press the Sample button when you are in
a menu other than Take calib. sample, the device begins
averaging the measurement results. A sample taken this
way can not be used to calibrate the device. Rather, it is
intended to be used to read the measurement result av-
erage over the desired period of time for monitoring
purposes, for example.
Installation & Owner’s manual OUL00298 V2.3 EN 29 Valmet Mircowave Consistency Transmitter